Metastatic lobular breast carcinoma to an endometrial polyp diagnosed by hysteroscopic biopsy

BACKGROUND: Secondary tumors involving the uterus are rare, and most come from the dose vicinity. Among nongynecologic origins, breast tumors are the most frequent, being predominantly of the lobular carcinoma type. CASE: A 69-year-old woman presented with metrorrhagia. The patient had been diagnosed 4 years before with infiltrating lobular breast carcinoma. Follow-up was uneventful. She underwent hysteroscopy with biopsy. An endometrial polyp was seen. Microscopically, small malignant cells diffusely infiltrated the endometrial stroma and surrounded the atrophic endometrial glands. Immunohistochemical studies confirmed die diagnosis of metastatic lobular breast carcinoma. CONCLUSION: Although rare, breast tumors can metastasize to an endometrial polyp, even in the absence of other disseminations. Abnormal vaginal bleeding in a patient with known breast carcinoma can be the first sign of metastasis.